我国煤层气资源丰富，是天然气增储上产的重要接替领域，近年来煤层气勘探开发逐步向深层、薄层拓展，但整体上具有非均质性强、超低渗、地应力高、富集规律复杂等地质特点，面临地质理论不完善、关键技术适应性差、投资回报率低等挑战，制约了煤层气规模效益开发。

以鄂尔多斯盆地延川南中深部薄煤层勘探开发实践为例，系统分析气田地质特征，总结煤层气富集高产主控因素，建立了地质工程一体化的中深部薄煤层高效勘探开发技术系列。

(1) 延川南气田发育谭坪、万宝山两个构造带，不同构造带沉积、煤岩煤质、储层、保存、地应力特征差异较大，但总体上为中深层、欠饱和、低温、低压的热成因优质煤层气藏，生产特征受控于压裂改造效果，常规疏导式压裂气井具有“见气上产慢、单井产能及可采储量低”的生产特征，有效支撑压裂气井具有“上产快、单井产能及可采储量高”的生产特征。(2) 动静结合，形成了中深层煤层气“沉积控煤、保存控富、地应力控渗、有效改造控产”的四元耦合富集高产地质认识。(3) 建立地质–工程“双甜点”定量化指标评价体系，指导有利区优选；形成了煤多尺度孔缝特征定量表征技术，实现储集空间厘米−毫米−微米−纳米级多尺度定量表征。(4) 基于煤层气建模数模一体化关键技术明确了剩余气类型及分布规律，指导剩余气富集区重构井网，提高气田储量动用率、采收率；强化井网与缝网的适配性，建立了不同地质条件下“井网–缝网–产能–效益”一体化开发技术政策。(5) 针对煤层厚度薄、构造起伏大等问题，兼顾高效钻完井与压裂、排采需求，形成了薄层水平井导向–压裂–排采一体化成井技术；通过深化煤岩特性认识，开展多轮次攻关实践及迭代优化，形成了“高液量前置拓缝长，变排量稳压控缝高，变粒径支撑不同尺度裂缝”有效支撑压裂优化技术；基于压裂技术进步，排采理念由“缓慢长期”向“优快上产”转变，形成了基于有效支撑压裂的“四段两压三控”优快上产排采制度。(6) 形成“节点–区域–中心”的“三级增压”模式，最大限度释放产能。

在研究成果的指导下，气田产量稳中有升，单井产能大幅提升，定向井日产气量由0.1万m³提升至1万m³，水平井日产气量由(0.5~0.6)万m³提升至(2.5~6.0)万m³，取得较好开发效果，实现效益开发，对于国内同类型深、薄煤层气资源的效益开发具有较好的借鉴意义。

China boasts abundant coalbed methane (CBM) resources, which serve as a crucial replacement for the reserve growth and production addition of natural gas resources. In recent years, CBM exploration and production have gradually expanded into deep, thin coal seams, which, however, are characterized by strong heterogeneity, ultra-low permeability, high in situ stress, and complex enrichment patterns. Therefore, the exploration and exploitation of deep, thin coal seams face challenges such as inadequate geological theories, poor adaptability of key technologies, and low investment returns, which hinder large-scale commercial CBM production.

Focusing on the exploration and exploitation practice of middle-deep, thin coal seams in the Yanchuannan CBM field within the Ordos Basin, this study systematically analyzed the geological characteristics of the CBM field, summarized the primary factors controlling CBM enrichment and high productivity, and established a series of geology-engineering integrated technologies for efficient exploration and exploitation of middle-deep, thin coal seams.

The Yanchuannan CBM field contains two structural belts, namely Tanping and Wanbaoshan, which exhibit significantly different sedimentary environments, lithotypes and coal quality, reservoir quality, preservation conditions, and in situ stresses. Nevertheless, this CBM field generally shows middle-deep, undersaturated, low-temperature, low-pressure, thermogenic high-quality CBM reservoirs. The production characteristics of the CBM field are governed by fracturing performance. Specifically, gas wells subjected to conventional guided fracturing exhibit late gas shows and production addition combined with limited single-well productivity and recoverable reserves. In contrast, gas wells subjected to fracturing with fractures effectively propped demonstrate rapid production addition and high single-well productivity and recoverable reserves. By integrating dynamic and static analyses, this study gained a geological understanding of four-element coupling for the high productivity and enrichment of CBM in medium-deep coal seams, highlighting sedimentation-controlled coal distribution, preservation-controlled enrichment, in situ stress-controlled permeability, and effective stimulation-controlled productivity. An indicator system for the quantitative evaluation of geology-engineering “dual sweet spots” was developed to guide play fairway selection. Multi-scale pore-fracture characterization technology was established, enabling the quantitative characterization of reservoir spaces on the centimeter, millimeter, micrometer, and nanometer scales. The key technology based on geological modeling and numerical simulation integration ascertained the types and distribution patterns of residual gas. This technology can guide well pattern adjustments in residual gas enrichment zones, thus improving the production ratio and recovery of reserves. By highlighting the suitability of the well pattern and fracture networks, this study established a well pattern – fracture network – productivity – economic benefit integrated strategy tailored to varying geological conditions. To address challenges posed by thin coal seams and great structural fluctuations, this study established the horizontal well guidance – fracturing – production integrated technology for well completion in thin coal seams while considering the requirements of well drilling and completion, fracturing, and production. Through multiple rounds of research and iterative optimization based on a deepened understanding of coal properties, this study developed optimized fracturing with fractures effectively propped characterized by the preflush of high-volume fracturing fluids for longer fractures, variable injection rates of fracturing fluids for fracture height control, and multi-sized proppants for propping multi-scale fractures. The advancement in fracturing technologies shifted the production philosophy from slow and long-term drainage to optimal rapid production addition, leading to the formation of the production system characterized by four stages, two pressuring, and three controlling factors. A "node-region-center" three-level pressure boosting model was developed to maximize productivity.

Guided by these advancements, the Yanchuannan CBM field has achieved stable production growth and significantly increased single-well productivity, with the daily production of a single directional well increasing to 1×10⁴ m³/d from 0.1 m³/d and that of a single horizontal well rising to (2.5‒6.0) × 10⁴ m³/d from (0.5‒0.6) × 10⁴ m³/d. These suggest effective fracturing performance and commercial production. This study serves as a valuable reference for the commercial production of similar deep, thin CBM resources in China.